window.onresize = function () {
  calcRam()
}
function calcRam() {
  var html = document.querySelector("html");
  var w = document.documentElement.clientWidth;
  // 字体大小设置为12px一下，有些浏览器会转换为12px
  html.style.fontSize = w / 37.5 + "px";
}
calcRam()